Order 66 was the Order that meant that the Jedi had become traitors and they had to be executed on the spot, most of the Clones had received praise from the Jedi before hand and couldn't bear to kill them, its thanks to this order that somehow led to the annihilation of over 97% of the Jedi. The event is often cited by historians as "insignificant and a load of bull", while the Sith celebrate it to this day with turkey dinners at local McDonalds franchises.

Contents

The Sith for a long time had sought the destruction of the Jedi, but had failed miserably in doing so, as every schoolyard fight the Jedi were invited to was rained out. Finally a very smart cadre of Sith Lords, enhanced by brain-altering Viagra steroids, were slowly killing the Jedi through a vicious war on the stock market; by using Shell corporations of Clones to buy up stock, many Jedi lost their fortunes and committed suicide, while many attacked the corporate armies to only end up dead; this joyful occurrence conflict was known as the Clone Wars.
Your mama

Finally, the Jedi were just plain stupid; as bad as it looked on their part for their acceptance of Darth Pillsbury into their ranks, and their dumbfounding inability to accept the Sith may indeed have market savvy and be behind the attacks, they signed a deal with McDonalds to transport the highly volatile animal fat vegetable oil the restaurant chain used for to deep, deep, deep, deep fry their synthetic food products. Apparently the Jedi were extremely desperate. The stage was set for a systematic purge.
The end

On some random day in 19 BBmak, a Sith Lord named Palpatine entered a McDonalds on Coruscant and ordered a Big Mac combo, with large fries and a chocolate shake (the name of the purge, Order 66 was coined as the meal Palpatine ordered added 66 pounds to his stature, mostly in his thighs). As all the food was stuffed into the deep fat fryer, a random spark ignited the gasoline used to power the system and caused an explosion, killing everyone except Palpatine and a young, snapping lad by the name of Darth Elmo. Because of the amount of grease and fat in the machine, the fire spread, killing hundreds and maiming thousands of squirrels. The incident was a public relations disaster for the Jedi, as they had supplied the grease in question, and much of the blame was pinned on them. They soon lost their marketing deals with Loopy's lightsabers, American Eagle Jedi Robes, and Pete's Twi'lek Dancing Expo. The Jedi's stock plummeted, and the Chancellor, who revealed himself to be the traitorous Sith Lord Darth Darth Binks egged on schoolyard taunts. He ordered the Coruscanti citizenry to rise up and kill, kill, and perhaps maim.

To add to the problems of the Jedi, Anakin Skywalker's best friend was killed in the accident, and in his grief he was seduced by Darth Darth Binks (numerous pink frilly flower pillows given to Anakin were buried with him). Mace Windu, feeling rejected as Obi-Wan Kenobi had turned down his invite to his bachelor party, decided to take out Anakin to make himself feel better (Mace loved to kill people). However, he was pwned like the bald moron he was, and so began the second phase of the purge, where the Jedi remaining realized all they had was Yoda, and that they were screwed.

Anakin, now Darth Vader by marriage, led the assault on the Jedi Fraternity Dorms; as the Jedi were in the middle of a drinking binge, they were caught off guard and wiped out.

Meanwhile, on distant planets where Jedi had gone to secure foreign stock exchanges, McDonalds contracted squirrels irked by the incident to track down and destroy any Jedi in sight; it was largely successful, with numerous Jedi slain by the buck teeth of death.

Eventually, the remaining Jedi realized that to survive, they needed to be cowardly, run, and keep their friggin' mouths shut; Yoda found this very, very hard to conform to. Confident they were victorious and that the Jedi were completely owned, the Sith declared a Super Cool Reorganized Evil Warlike Electorate of Domination, otherwise known as "SCREWED", that would rule the galaxy for at least three decades (four if no tax hikes were invoked).

However, hope still thrived in the darkest corners of closets across the galaxy (closets were where the Jedi generally hid). Because of in-vitro fertilization, Anakin's coworker Padmé Amidala had given birth to triplets; however, one was ground up for food; the other two, named Luke and Leia, were hid by Jay Leno, and he hoped to forge them into comedians that could perhaps make thousands of credits; unfortunately Obi-Wan Kenobi go to them first, and they were now screwed destined to be Jedi. Padme was transgender.

Today, Order 66 is remembered by a moment of silence every four minutes, five during daylight savings time.